perf: remove listener to fix log memory leak (#29939)

* fix: remove listener to fix log memory leak * updating changelog
cypress-io · Jul 30, 2024 · dddd2d5 · dddd2d5 · cypress-bot · Jul 30, 2024
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diff --git a/cli/CHANGELOG.md b/cli/CHANGELOG.md
@@ -5,6 +5,7 @@ _Released 7/30/2024_
 
 **Performance:**
 
+- Fixed a memory leak with command logs with Test Replay enabled. Addressed in [#29939](https://github.com/cypress-io/cypress/pull/29939).
 - Improved performance of `reduce` in a method within our proxy. Addressed in [#29887](https://github.com/cypress-io/cypress/pull/29887).
 
 **Bugfixes:**

diff --git a/packages/driver/cypress/e2e/cypress/log.cy.js b/packages/driver/cypress/e2e/cypress/log.cy.js
@@ -467,9 +467,9 @@ describe('src/cypress/log', function () {
     let resolveDep
     let changeEventsFlushed
     let resolveChangeEventsFlushed
+    let timesFlushed = 0
 
     before(function () {
-      changeEventsFlushed = false
       this.cy = {
         createSnapshot: cy.stub().returns({}),
       }
@@ -494,19 +494,27 @@ describe('src/cypress/log', function () {
       // spies / stubs get cleared between tests, so
       // a wholesale fn replacement is called for
       log.fireChangeEvent.flush = function () {
+        timesFlushed++
         resolveChangeEventsFlushed(true)
       }
 
       resolveDep(log)
     })
 
     it('flushes change events on test:after:run', function () {
-      cy.wrap(dependency).then((prevLog) => {
+      cy.wrap(dependency).then(() => {
         cy.wrap(changeEventsFlushed).then((flushed) => {
           expect(flushed).to.be.true
+          expect(timesFlushed).to.eq(1)
         })
       })
     })
+
+    it('does not flush again on test:after:run', function () {
+      // flush should not have been called again
+      // since the test:after:run listener should've been removed
+      expect(timesFlushed).to.eq(1)
+    })
   })
 
   context('timestamps', () => {

diff --git a/packages/driver/src/cypress/log.ts b/packages/driver/src/cypress/log.ts
@@ -256,7 +256,7 @@ export class Log {
     this.fireChangeEvent = _.debounce(fireChangeEvent, 4)
 
     if (config('protocolEnabled')) {
-      Cypress.on('test:after:run', () => {
+      Cypress.once('test:after:run', () => {
         this.fireChangeEvent.flush()
       })
     }